Shutter structure for motion picture machines



Jan. '19, 1937. P. J. BERGGREN 2,068,259

SHUTTER STRUCTURE FOR MOTION PICTURE MACHINES Original Filed Dec. 20, 1928 IN VEN TOR;

3? 1 Am T ATTORNEYS.

Patented Jan. 19, 1937 UNITED STATES PATENT OFFICE- SHUTTER STRUCTURE Eon MoTIoN PICTURE MACHINES Per Johan Berggren, New York, N. Y.

lClaims. (oi. 8819.3)

This invention relates to motion picture machines and with particularity to methods and means for light shuttering.

An object of the invention is to provide an improved method of shuttering the light passed through the projection aperture of a motion picture projecting machine.

A further object of the invention is to provide methods and means to secure the gradual fading out of one projection picture and the accelerated uncovering or fading in of the next succeeding picture to be projected.

A further object is to secure the gradual fading out of one picture and the accelerated uncovering of the next succeeding one by or through the action of the shutter.

I A feature of the invention relates to a novel shutter structure for securing gradual fadeout and fade-in of projected pictures.

Other features and advantages not specifically enumerated will be apparent after a considera tion of the following detail descriptions and the appended claims.

Referring to the accompanying drawing:

2 Figure l is a front view of a shutter according to the invention; this figure also shows a portion of the projector head;

Fig. 2 is a side view of the mechanism disclosed in Fig. 1.

30 While the invention is capable of general use in known types of projecting apparatus, it is disclosed herein as applied to a projector of the type described in detail in application Serial No. 327,200 to which reference may be had for 'a de- 35 tail description of the parts of the projector not specifically disclosed herein.

The fundamental purpose in view in the present invention is to effect the change from one picture to the next succeeding one, at the rate 40 ordinarily employed of sixteen, more or less, per second, without causing any flicker or movement of the projected picture while the shift is being made. I have already described in application Serial No. 327,200 the action of the intermittent 5 feed as effecting a shift of the film from one stationary position into the next succeeding stationary position, in bringing successive pictures into projecting relation in approximately onehalf the time interval heretofore required. The

50 shutter action must, coordinate with that of the intermittent feed, and in such a manner as to secure a smooth fade-out of the one picture and likewise a fade-in of the next succeeding picture. Even if the intermittent film feed ac- 55 tion referred to is not employed, the fading-out and fading-in of successive pictures 'of the film is most desirable in order to avoid a flicker orvibration of the projected pictures at the instant of the shift, and also 'to avoid an abrupt -change from light to dark and from dark to light by the action of the shutter. Such abrupt changes with the resultant flicker are exceedingly objectionable in that it not only spoils the picture but is also injurious to the eyes of the observers" In accordance with the principles of the present invention it is proposed to avoid this flicker action by providing a peculiar formation of the approaching and receding edges of the shutter blades which will secure a gradual fade-out of the picture last to be projected and a gradual fadein of the picture next to be projected.

In the drawing there is shown a portion of a projector head comprising an upper casing II3 for enclosing the pay-off reel for the motion picture film, and a lower casing containing the receiving or take-up reel. The projector housing 12 is intermediate the said reels and carries the various mechanisms for advancing the film under control of the main vertical driving shaft '9I.

Shaft 9| is adapted to be operated in a continuous manner from a suitable power source.

For this purpose it is coupled to the said source through the gear train 11, I8 and 80. Disposed at right angles to the main shaft BI is a shaft 95 which is driven from shaft 9| through the bevel gears 94. Shaft III also drives a set of bevel gears 91 which control the intermittent feeding mo.-

.tion of the film as described in application Serial No. 327,200. Shaft 95 extends beyond the wall of the housing 12 and has attached thereto a shutter 96 comprising a set of three blades I15, all of similar shape.

In the drawing there is shown one form of shutter structure as a practical embodiment of my invention, wherein the shutter is provided with three blades I15, though in this respect my invention is not to be limited or restricted.

The approaching or forward edge of each blade 7 is formed with a tapering projection I16, disposed in position to initially penetrate the center of the bundle of light rays projected from the lens Just screen. Therefore, in order to securethat result, I provide the rear or what may be termed the receding edge of the shutter blade with a tapering recess I", having the same relation to the center line of the bundle of light rays from the lens as the tapering projection I16 on the forward edge of the shutter, that is to say, while the projection "6 on the forward edge of the blade initially obscures the central portion of the bundle or rays with a successive increase in obscuring area, the recess I" in the rear edge gives an initial opening up of the light rays from the lens with a successive increase in the removal of the obscuring relation of the blade.

The blades should all be of equal area to give the best results. In caseit is desired to employ a shutter having only two blades then the area of each blade should be approximately equal to the area of each shutter opening or space between the proximate edges of adjacent blades. Too many blades result in cutting oil! too much light which.means loss of illumination or brilliancy on the screen which is objectionable.

By the provision of the pointed and tapering projection on the advancing or forward edge and the reversely outlined pointed and tapering re- ,cesson the recedingorrear edge of-the same blade not only are the fade-out and fade-in eil'ects secured but there is effected a smooth, easy transition from light to dark and from dark to light, and a softening of the contrast which is restful to the eyes of the spectator and enaooaaso hances the beauty and fidelity of the projected picture. These are results which are impossible of attainment with square edged shutter.

This application is a division of application Serial No. 327,200, flied December 20, 1928.

What is claimed is:

1. In a motion picture projecting apparatus, a shutter having blades, each blade having a projection on the advancing edge thereof and a recess in the receding edge thereof, the outline of the projection and the recess being the same.

2. In a motion picture projecting apparatus, a shutter having blades, each blade having a single projection on the advancing edge thereof and a single recess in the receding edge thereof, said projection and recess being pointed.

3. In a motion picture projecting apparatus, a shutter having blades, each blade having a projection on the advancing edge thereof and a recess in the receding edge thereof, said projection and recess being located to intercept first the y 

